I'm running Clang v5.0.1, originally on Qt Creator 4.5.0, but it behaves the same on 4.6.0 Beta1-1871. A simple hello-world application:
int main(int, char*)
std::cout << "Hello World" << std::endl;
This obviously compiles and runs fine under GCC, but the CCM marks every line as some kind of error. Enabling CCM debug for Qt Creator reveals some interesting things: Clang cannot seem to find a header file despite looking in the correct place:
#include "..." search starts here:
#include <...> search starts here:
End of search list.
Parsing /home/cmannett85/workspace/calrec/scratch/main.cpp: 0.1768 (100.0%) 0.0106 (100.0%) 0.1874 (100.0%) 0.1895 (100.0%)
/usr/include/c++/7/cstdlib:75:15: fatal error: 'stdlib.h' file not found
stdlib.h is in /usr/include, but for some reason Clang just doesn't see it. I've attached the complete clang debug output.